Joint replacement surgery is quite common and it enables many individuals to function properly when it would not otherwise be possible to do so. Such patients of joint replacement surgery typically suffer from osteoarthritis or rheumatoid arthritis. Artificial joints usually comprise metallic, ceramic and/or plastic components that are fixed to existing bone.
Such joint replacement surgery is otherwise known as total joint arthroplasty. Total joint arthroplasty is a well known surgical procedure by which a diseased and/or damaged joint is replaced with a prosthetic joint. In a typical total joint arthroplasty, the adjacent ends of the bones and cartilage comprising the joint are resected and the artificial implants are secured thereto.
When only one part of the knee joint is damaged, only the damaged compartment is resected and replaced. This is known as a uni-compartmental knee joint arthroplasty.
When only the patellar articular surface and the adjacent groove on the distal end of the femur, the trochlear, with which it articulates, are damaged, replacement of these surfaces is called a patello femoral arthroplasty.
Frequently, when installing the components of the prosthetic joint, cartilage and bone must be resected or removed such that the implanted prosthesis has the same surface profile as the surface prior to its resection. Such arthroplasty thus requires a pocket formed in the bone of a particular shape and depth to provide a location for the prosthesis such that the prosthesis outer-profile replicates that of the pre-resected joint. Among such joints for which a resected pocket is required is a trochlear implant for cooperation with a patella prosthesis for a patello femoral arthroplasty.
The current process for preparing to implant a trochlear prosthesis is to place a template over the femur where the damaged trochlear is located. The trochlear groove of the femur is then physically marked with a tool such as a scribe or marking pen which leaves a mark on the bone or cartilage as the scribe or pen is moved about the periphery of the template. The traced marks on the distal femur serve as a guide for preparing the pocket for the trochlear implant. Osteotomes and hammer plus high-speed rotating burrs are then used to prepare the pocket within the outlined perimeter. This process is very slow and tedious in order to achieve a precise and accurate fit in all dimensions.
A need thus exists for an improved method and instrumentation to assist in the implanting of a trochlear prosthesis or similar implants, which are placed in the bone at a depth to conform to the pre-resected contour of the bone.